Free software, FOSS or Open source is software that is distributed in a manner that allows its users to run the software for any purpose, to redistribute copies of, and to examine, study, and modify, the source code.

Software manuals must be free, for the same reasons that software must be free, and because the manuals are in effect part of the software. The same arguments also make sense for other kinds of works of practical use — that is to say, works that embody useful knowledge, such as educational works and reference works. Wikipedia is the best-known example. Any kind of work can be free, and the definition of free software has been extended to a definition of free cultural works applicable to any kind of works.

My work on free software is motivated by an idealistic goal: spreading freedom and cooperation. I want to encourage free software to spread, replacing proprietary software that forbids cooperation, and thus make our society better.

There is no such thing as free software. Nobody develops software for charity. For innovation to continue, there needs to be value - and even open-source applications have some form of market model, which incentivises them to continue innovating.

The GNU GPL is not Mr. Nice Guy. It says "no" to some of the things that people sometimes want to do. There are users who say that this is a bad thing--that the GPL "excludes" some proprietary software developers who "need to be brought into the free software community." But we are not excluding them from our community; they are choosing not to enter. Their decision to make software proprietary is a decision to stay out of our community. Being in our community means joining in cooperation with us; we cannot "bring them into our community" if they don't want to join. What we can do is offer them an inducement to join. The GNU GPL is designed to make an inducement from our existing software: "If you will make your software free, you can use this code." Of course, it won't win 'em all, but it wins some of the time.

For example, the GPLv2 in no way limits your use of the software. If you're a mad scientist, you can use GPLv2'd software for your evil plans to take over the world ("Sharks with lasers on their heads!!"), and the GPLv2 just says that you have to give source code back. And that's OK by me. I like sharks with lasers. I just want the mad scientists of the world to pay me back in kind. I made source code available to them, they have to make their changes to it available to me. After that, they can fry me with their shark-mounted lasers all they want.

So the whole 'We have a list and we're not telling you' should tell you something. Don't you think that if Microsoft actually had some really foolproof patent, they'd just tell us and go, 'nyaah, nyaah, nyaah!'?

Linus Torvalds, Said about Microsoft's claim that the Linux kernel infringes upon 42 of their patents.

Nobody should start to undertake a large project. You start with a small _trivial_ project, and you should never expect it to get large. If you do, you'll just overdesign and generally think it is more important than it likely is at that stage. Or worse, you might be scared away by the sheer size of the work you envision. So start small, and think about the details. Don't think about some big picture and fancy design. If it doesn't solve some fairly immediate need, it's almost certainly over-designed. And don't expect people to jump in and help you. That's not how these things work. You need to get something half-way _useful_ first, and then others will say "hey, that _almost_ works for me", and they'll get involved in the project.

The legal system doesn't work. Or more accurately, it doesn't work for anyone except those with the most resources. Not because the system is corrupt. I don't think our legal system (at the federal level, at least) is at all corrupt. I mean simply because the costs of our legal system are so astonishingly high that justice can practically never be done.

I bumped into him (Craig Mundie of Microsoft) in an elevator. I looked at his badge and said, "ah, you work for Microsoft." He looked back at me and said, "Oh ya, and what do you do?" And I thought it was some kind of tad dismissive, here is a guy in a suit looking at a scruffy hacker... so I gave him a thousand yard stare and said, "I am your worst nightmare!"

This existing base of FLOSS software represents a lower bound of about 131,000 real person-years of effort that has been devoted exclusively by programmers. As this is mostly by individuals not directly paid for development, it represents a significant gap in national accounts of productivity. Annualised and adjusted for growth this represents at least Euro 800 million in voluntary contribution from programmers alone each year, of which nearly half are based in Europe.

Firms have invested an estimated Euro 1.2 billion in developing FLOSS software that is made freely available. Such firms represent in total at least 565,000 jobs and Euro 263 billion in annual revenue. Contributing firms are from several non-IT (but often ICT intensive) sectors, and tend to have much higher revenues than non-contributing firms.

"Sharing the code just seems like The Right Thing to Do, it costs us rather little, but it benefits a lot of people in sometimes very significant ways. There are many university research projects, proof of concept publisher demos, and new platform test beds that have leveraged the code. Free software that people value adds wealth to the world."

I personally believe open source is most important is in the operating system and in file formats. As long as those two things remain open source you can never have a monopoly. No company can dominate by any means except a superior product, and that puts the choice back into the hands of the public.

Another group has started using the term “open source” to mean something close (but not identical) to “free software”. We prefer the term “free software” because, once you have heard that it refers to freedom rather than price, it calls to mind freedom. The word “open” never refers to freedom.